With the advance of semiconductor technologies and the like, the performance of CPUs and processors used in mobile devices has been improved remarkably. For example, an operating frequency of the level of GHz has been used widely in mobile phones. When the system speed and core requirements reach higher limits, the power consumption of CPUs and processors is also increasing. As a result, more and more heat needs to be dissipated in the limited space of a mobile phone in order to control the skin surface temperature (Tskin) of the mobile phone.
Thermal management is one of the key challenges in the design of today's mobile devices, such as smartphones. The power consumption in smart devices have grown exponentially compounded by the needs for higher data rate, more multitasking applications, and the increasing number of background tasks for popular applications such as email and social networking. The higher performance requirement for the smart devices means peak maximum throughput is frequently required. It leads to higher clock frequencies, which inevitably generates more heat from various integrated circuits (ICs) and/or other components in the device. Currently, each IC may contain one or more heat-generating components. With increasing number of components running at high clock frequencies inside a small compact device, heat dissipation requires advanced solutions for thermal management.
FIG. 1 shows a current method of thermal management. It illustrates a temperature curve under thermal throttle. As shown, a threshold temperature, namely Tbound is configured for a mobile device, such as a mobile phone, a tablet, a wearable device, a laptop, etc. The mobile device monitors the temperature starting from t0. As the data throughput or processing power in the device increases, the temperature of the device starts to increase. In many situations, the high demands for faster data rate, faster and better graphical processes from an application compounded with large number of background running tasks requires high frequencies from various components/ICs of the device. The heat dissipation in a small, compact smart device, such as smartphone is much harder because the area to dissipate the heat is limited. Therefore, the temperature of the device increases quickly. In the current thermal management, there is no power throttling until the temperature reaches the predefined or preconfigured threshold temperature Tbound. As a result, at time t1, the temperature reaches the preconfigured threshold Tbound. Upon detecting the temperature rises to the preconfigured threshold Tbound, the device starts thermal throttle by controlling the power of the ICs or components of the device that generates heat. Since the throttle takes time, the temperature continues to rise after t1. At time t2, the temperature starts to drop because the power throttling of the devices reduces the heat sources. At time t3, the temperature drops back to the preconfigured threshold Tbound. With the throttling for thermal control starts, the temperature of the device bounces near the preconfigured temperature Tbound as shown in FIG. 1.
The problem of the current thermal management for smart devices is that it causes large performance degradation. The current method controls heat generation components or ICs in the device for thermal throttling. Such process may greatly reduce the performance of the smart device. For example, one way to reduce heat generation of a ICs or components of the smart device is to lower its operation frequency, which results in lower processing speed. The problem aggravates with the increasing demands for high performance of the smart devices. For example, to control the temperature, the throttling lower the clock frequency, which results in less processing power for data throughput, which results in backlog queues of pending processing. When the temperature reaches an acceptable level, the backlog data, together with continuous tasks, requires high performance of the device. Such high performance on the devices makes the temperature fast approaching the preconfigured threshold Tbound again, which requires performance-degraded throttling.
Enhancement and improvements are needed to prevent the device to reach the Tbound too fast. A more efficient way of thermal management for mobile devices is required.